Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems. Typically, a wireless communication system comprises several base stations (also referred to as access point), wherein each base station communicates with the mobile station using a forward link and each mobile station communicates with base station using a reverse link.
Multiple access communication systems often employ a method of assigning specific channel resources for use by one or more terminals or access terminals (ATs). The resource may be a time slot, spreading code, frequency band, etc. Both forward and reverse link traffic channels may be assigned to terminals by messages transmitted to the terminals via a shared or broadcast control channel. Further, traffic channels may also be explicitly deassigned by transmitting deassignment messages to terminals when the network needs to use the resource for another user, or purpose. Alternatively, traffic channels assignments may be explicitly deassigned after each use of the channel (after each packet transmission). Often, the resources required by this control channel are high, and limitations on the control channel limit the ability of the network to effectively manage the assignment of traffic channels and to maximize the efficiency of the network.
In a typical communications system, such as OFDMA, the certain resources are typically allocated to users on a temporary basis. The base station provides indication to the users (one or more access terminals in communication with the base station) have explicit assignment and also provide an indication to the users of explicit de-assignment. Typically, a base station transmits an assignment that is deassigned automatically after packet transmission/reception. This removes the deassignment message requirement, but would require an assignment for each channel use, even if the user needs a “continuous” assignment, or “semi-continuous” assignment. This requires several exchanges between the user and the base station. Generally, the base station transmits a deassignment message requesting the user to discontinue the use of resources. Upon receiving and acknowledgement message, the base station allocates those resources to a new user by transmitting and assignment message. Deassignments are important to prevent collisions of traffic and/or feedback channels, which can severely limit network performance. However, transmitting de-assignments and assignments increases assignment traffic and lower efficiency in the system. In a system that uses a channel for providing assignments to all users in the system, it is important that the traffic on this channel be monitored efficiently. Thus, using implicit assignments that allows the network to avoid sending redundant information would be preferred.
Therefore, a method is needed to reduce the number of assignment traffic between the base station and the user.